Question

read each example and decide whether each would increase or decrease the genetic variation in the gene pool of that population. a zebra migrates to join a different herd of zebras. increase decrease competition for sunlight leads to taller trees. the dna of a snake changes to make its venom stronger. a grassfire randomly sweeps through a population of buffalo and kills most of the animals. done

Explanation:

1. For "A zebra migrates to join a different herd of zebras": Migration (gene flow) introduces new genes, so it increases genetic variation. So the answer is Increase.
2. For "A grassfire randomly sweeps through a population of buffalo and kills most of the animals": This is a bottleneck effect, reducing the number of individuals and thus decreasing genetic variation (since many alleles are lost). So the answer is Decrease.

Answer:

1. A zebra migrates to join a different herd of zebras: Increase
2. A grassfire randomly sweeps through a population of buffalo and kills most of the animals: Decrease